The THALIA-T 90 mm has a dreamlike, romantic soft-focus look, and a high contrast, realistic look by stopping down the aperture. A characteristic bokeh is created by intentionally under correcting spherical aberrations along with a circular iris for the circular reproduction of blurred highlight. The aberration increases towards the periphery of the optical system, that is why both, the extension of the depth of field and the degree of diffusion, can be precisely controlled via the aperture. Widening the aperture increases the soft focus, while stopping down reduces the effect.